Search Results (4)

“Horchata” is a well-known Spanish beverage obtained from pressing tiger nuts. Its by-product is a potential source of sugar and fiber but also contains polyphenols; thus, it could be used as a new ingredient in the food industry. The aim of this work is to determine the phenolic compounds and compare the phenolic profile of two tiger nut by-products. A Box–Behnken design has been carried out to optimize the extraction of phenolic compounds from tiger nut by-products by ultrasound technology. The independent factors were time (min), ethanol/water (% v/v), and solvent/sample ratio (v/w). The model was validated and confirmed by ANOVA. A Protected Designation of Origin (PDO) of Valencia and a non-Protected Designation of Origin (n-PDO) tiger nut by-products were extracted under the optimal conditions and were characterized by HPLC-DAD-ESI-TOF-MS (High Performance Liquid Chropatography coupled to a photodiode array time-of-flight mass detector). Moreover, their antioxidant activities measured by three different methods (DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2′-Azinobis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt) and FRAP (ferric reducing antioxidant power)) were compared. A total of 45 polar compounds were identified, and the phenolic ones were quantified, some of them for the first time. PDO tiger nut by-product has been demonstrated to be richer in phenolic acids and other polyphenols and has higher antioxidant activity; meanwhile, n-PDO tiger nut by-product is richer in phenol precursors. Full article

Carbohydrate-rich byproducts may be used as a growth substrate for microalgae. The tiger nut, compared to other tubers, has higher carbohydrate content, which mostly remain in the byproduct after the production of tiger nut milk (“Horchata”). The aim of this study is the optimization of a hydrolysis pre-treatment in tiger nut byproduct to obtain reducing sugars, objective framed in the European SUSPUFA (Sustainable production of health-promoting n-3 LC-PUFA using agro-food industry by-products through microalgae) Project. Two experimental 4-factor Box–Behnken designs (acid concentration (N), temperature (°C), time (min) and ratio acid/sample) were carried out with 27 experiments to optimize chemical hydrolysis conditions with H₂SO₄ and H₃PO₄ in duplicate. The sugars were determined by the Schoorl method and the extracts obtained by the optimal conditions were analyzed by high-performance liquid chromatography (HPLC). Protected designation of origin (PDO) and non-protected designation of origin (n-PDO) tiger nut byproducts were characterized by physicochemical methods. The validity of the experimental designs was confirmed by ANOVA. The optimum sugar values were obtained with H₂SO₄ 2 N at 85 °C, 60 min and ratio 60 and H₃PO₄ 21 N at 90 °C, 60 min and ratio 60. Glucose and xylose were the sugars detected in the hydrolyzed samples. In conclusion, almost 50% of the total carbohydrates present in the tiger nut byproduct were hydrolyzed to reducing sugars. Full article

The aim of this study was to assess the effect of temperature, solvent (hydroethanolic mixtures) and pH on the recovery of individual phenolic compounds from “horchata” by-products. These parameters were optimized by response surface methodology and triple-TOF-LC-MS-MS was selected as the analytical tool to identify and quantify the individual compounds. The optimum extraction conditions were 50% ethanol, 35 °C and pH 2.5, which resulted in values of 222.6 mg gallic acid equivalents (GAE)/100 g dry matter and 1948.1 µM trolox equivalent (TE)/g of dry matter for total phenolic content (TPC) and trolox equivalent antioxidant capacity (TEAC), respectively. The extraction of phenolic compounds by the conventional solvent method with agitation was influenced by temperature (p = 0.0073), and more strongly, by the content of ethanol in the extraction solution (p = 0.0007) while the pH did not show a great impact (p = 0.7961). On the other hand, the extraction of phenolic acids was affected by temperature (p = 0.0003) and by ethanol amount (p < 0.0001) but not by the pH values (p = 0.53). In addition, the percentage of ethanol influenced notably the extraction of both 4-vinylphenol (p = 0.0002) and the hydroxycinnamic acids (p = 0.0039). Finally, the main individual phenolic extracted with hydroethanolic mixtures was 4-vinylphenol (303.3 μg/kg DW) followed by spinacetin3-O-glucosyl-(1→6)-glucoside (86.2 μg/kg DW) and sinensetin (77.8 μg/kg DW). Full article

During the production of a traditional drink produced from the tubers of Cyperus esculentus L. also known as “horchata de chufa,” a high quantity of by-products are generated. These by-products are rich with valuable biological compounds, hence, there is a need to report their extraction conditions for further use in food production as raw materials. Therefore, the objective of this study was to evaluate and improve the conventional extraction process, applied for recovery of phenolic compounds, total flavonoids, and total antioxidant capacity from the by-products. Independent variables for extraction were: (i) Solvent type (mixtures of ethanol-water (v/v) at 0%, 25% and 50%); (ii) temperature (40, 50 and 60 °C), and (iii) extraction time (1, 2 and 3 h). The obtained results showed that solvent type, temperature, and time significantly influenced (p < 0.05) all investigated parameters. The highest content of total polyphenols (16.02 mg GAE/100 g of dry matter; d.m.), and total flavonoids (30.09 mg CE/100 g d.m.) was achieved by ethanol at 25% (v/v), after 3 h of extraction with temperatures of 60 °C and 50 °C, respectively. The highest value of antioxidant capacity (1759.81 µM Trolox equivalents/g d.m.) was observed with 50% aqueous ethanol (v/v), at 60 °C, and 3 h of extraction. From the obtained results, it can be concluded that the by-products of “Horchata de Chufa” are an important source of antioxidant bioactive compounds. Full article